In 2006, a panel of experts assembled by the World Small Animal Veterinary Association (WSAVA) published guidelines for the standardization of clinical and histologic subtypes of liver disease in small animals.1 These guidelines state that a histologic diagnosis of chronic hepatitis requires the presence of hepatocellular apoptosis or necrosis, a mononuclear or mixed inflammatory infiltrate, hepatocyte regeneration, and fibrosis. Primary chronic hepatitis is clinically diagnosed after identification of these characteristic histopathologic findings and exclusion of secondary causes of chronic hepatitis, including associated toxins, infectious agents, and primary metabolic defects (i.e. copper-associated chronic hepatitis).
Erika Meler, DVM, MS
Although previous studies have examined a variety of clinicopathologic and histopathologic variables in dogs with secondary chronic hepatitis or chronic hepatitis of all types, no prognostic factor has been identified as of yet in dogs with primary chronic hepatitis. Because ascites is a well-recognized negative prognostic factor in people with liver disease, the authors' goal was to compare survival times in dogs with primary chronic hepatitis with or without ascites.
Barrak Pressler, DVM, PhD, DACVIM
In this retrospective study, 34 dogs with clinically and histologically confirmed primary chronic hepatitis were identified by medical records review, exclusion of dogs with suspected or confirmed secondary causes of liver disease, and review of original histologic sections of liver by one veterinary pathologist who was blinded to the clinical information. Information collected for each dog included signalment, date of onset of clinical signs, date of liver biopsy acquisition, the presence or absence of ascites at the time of biopsy, drugs administered, patient outcome (survival or death or euthanasia from liver-related or unrelated disease), and date of death.
Free abdominal fluid (ascites) had been noted in 14 of the 34 dogs and was confirmed to be either a pure or modified transudate in the 11 samples submitted for cytologic examination. Kaplan-Meier survival analysis revealed that the mean survival time was significantly different between the two groups regardless of the date of onset of liver-related clinical signs or the date of biopsy. The median survival of patients that died of liver-related causes from the date of biopsy was 24.3 months for dogs without ascites vs. 0.4 months for dogs with ascites (P < 0.001, meaning that this finding was highly statistically significant). In addition, patients in the nonascitic group were more likely to have been prescribed a liver-specific diet, whereas patients in the ascitic group were more likely to have been prescribed spironolactone.